TY - JOUR
T1 - Evaluating the effectiveness of the phosphorus sorption index for estimating maximum phosphorus sorption capacity
AU - Bolster, Carl H.
AU - McGrath, Josh M.
AU - Rosso, Emileigh
AU - Blombäck, Karin
N1 - Publisher Copyright:
© 2020 The Authors. Soil Science Society of America Journal © 2020 Soil Science Society of America
PY - 2020/5/1
Y1 - 2020/5/1
N2 - The single-point P sorption index (PSI), which is defined as the ratio of sorbed P (S) to the log P concentration in soil solution following a single P addition, is often used to estimate maximum soil P sorption capacity (Smax). Although studies have found good correlations between PSI and Smax as determined from fitting the Langmuir model to complete sorption isotherm data, a thorough analysis of the role of added P concentration on this relationship is needed. Our first objective was to investigate the effect of added P concentration on the correlation between PSI and Smax as determined by the Langmuir equation. Our second objective was to determine if S was better than PSI for predicting Smax. Using numerical simulations, we tested the correlation between Smax and PSI for added P concentrations of 75, 100, 150, and 200 mg P L−1. Results of the simulations show that the strength of the correlation between Smax and PSI increases with increasing P concentration. Our results also show that PSI was a better predictor of Smax than S for added concentrations of 75 and 100 mg P L−1, whereas at the higher rates S was a slightly better predictor of Smax and gave a direct estimate of Smax rather than the relative estimate obtained from PSI. Results from P sorption data measured on soils from Maryland and Sweden were consistent with our results from the numerical simulations. Our findings highlight important limitations of using PSI for estimating Smax.
AB - The single-point P sorption index (PSI), which is defined as the ratio of sorbed P (S) to the log P concentration in soil solution following a single P addition, is often used to estimate maximum soil P sorption capacity (Smax). Although studies have found good correlations between PSI and Smax as determined from fitting the Langmuir model to complete sorption isotherm data, a thorough analysis of the role of added P concentration on this relationship is needed. Our first objective was to investigate the effect of added P concentration on the correlation between PSI and Smax as determined by the Langmuir equation. Our second objective was to determine if S was better than PSI for predicting Smax. Using numerical simulations, we tested the correlation between Smax and PSI for added P concentrations of 75, 100, 150, and 200 mg P L−1. Results of the simulations show that the strength of the correlation between Smax and PSI increases with increasing P concentration. Our results also show that PSI was a better predictor of Smax than S for added concentrations of 75 and 100 mg P L−1, whereas at the higher rates S was a slightly better predictor of Smax and gave a direct estimate of Smax rather than the relative estimate obtained from PSI. Results from P sorption data measured on soils from Maryland and Sweden were consistent with our results from the numerical simulations. Our findings highlight important limitations of using PSI for estimating Smax.
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U2 - 10.1002/saj2.20078
DO - 10.1002/saj2.20078
M3 - Article
AN - SCOPUS:85085706934
SN - 0361-5995
VL - 84
SP - 994
EP - 1005
JO - Soil Science Society of America Journal
JF - Soil Science Society of America Journal
IS - 3
ER -